Metabolic pathways for nutritionally essential amino acids have become a prime focus of interest in herbicide discovery during recent years. This interest is due to the discovery of several classes of herbicides that are highly active, have low animal toxicity and were found to inhibit enzymes in these pathways. These herbicides inhibit enzymes in the pathways for branched chain amino acids (inhibited by imidazolinones, sulfonylureas and triazolopyrimidines), aromatic amino acids (inhibited by glyphosate), glutamine (inhibited by bialaphos and phosphinothricin) or histidine (inhibited by amitrole).
In traditional herbicide discovery, a chemical sample is sprayed on a whole plant and the effect of the chemical is scored after a set period of time, typically two to three weeks after application. Compounds that are identified from this approach must then be further characterized as to the spectrum of plants affected, toxicity and site of action. This process requires large amounts of the test compound, is time consuming, expensive and inefficient. Therefore, a rapid, small scale method for screening potential herbicides would be advantageous in herbicide development.